Hilo Airport
Aircraft Accident/Incident Report

Hilo, Hawaii 96720
Thursday, February 7, 2008 14:35 HST

NTSB Narrative Summary Released at Completion of Accident

The flight was approximately five miles from the departure airport when the pilot turned back due to a fuel bypass caution light. The pilot heard 2-3 abnormal engine sounds, with simultaneous yawing, during the turn and entered an autorotation. During the final stages of the autorotation, the engine flamed out. The helicopter touched down on uneven terrain and rolled over resulting in substantial damage. Post accident examination of the engine assembly revealed a fuel leak from the fuel filter pressure differential switch. The differential switch was in place and the associated fuel lines, bushing and adapter fitting were not damaged. Examination of the system revealed that one of the three fuel filter pressure differential switch set screws, and associated safety wire segment, was missing. The two remaining screws were in place. One of the screws was fixed, the other finger tight. The corresponding safety wire was attached to the remaining set screws. The distal end of the safety wire leading to the missing set screw was severed. A post accident evaluation of the engine in a production test cell revealed a fuel leak at the pressure differential switch when the engine was motored to 16 percent N1 (compressor speed). The original fuel filter pressure differential switch was removed and replaced with an exemplar differential switch. A second engine start was successful and the engine ran, without leaks, and attained normal operating parameters. Maintenance records indicated that the helicopter's fuel system components were inspected during the 100-hour inspection completed 66 flight hours before the accident. The maintenance "check sheet" indicated that the engine's fuel system components, to include fuel lines and connections, were inspected for leaks or damage, and no anomalies were noted. No record was found in the maintenance records of any work done to the fuel filter pressure differential switch subsequent to the 100-hour inspection. It could not be determined when, or how, the fuel filter pressure differential switch set screws, and associated safety wire came loose. The approved maintenance manual for the helicopter contains multiple warnings indicating that air in the closed fuel system will cause a power reduction or flame out.

NTSB Probable Cause Narrative

A leak in the fuel filter pressure differential switch that resulted in a loss of engine power. Contributing to the accident was uneven terrain that hindered a successful emergency landing.

Event Information

Type of Event Accident
Event Date 2/7/2008
Event Day of the Week Thursday
Time of Event 1435
Event Time Zone Hawaii Standard Time
Event City Hilo
Event State HAWAII
Event Country --
Zipcode of the event site 96720
Event Date Year 2008
Event Date Month 2
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude 194241N
Event Location Longitude 1550855W
Event Location Airport Hilo
Event Location Nearest Airport ID PHTO
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness --
Investigator's weather source Pilot
Time of the weather observation
Direction of event from weather observation facility (degrees) --
Weather Observation Facility ID --
Elevation of weather observation facility --
Distance of event from weather observation facility (units?) --
Time Zone of the weather observation --
Lighting Conditions Day
Lowest Ceiling Height 2000
Lowest Non-Ceiling Height 1500
Sky/Lowest/Cloud Conditions Scattered
Sky Condition for Lowest Ceiling Broken
Visibility Runway Visual Range (Feet) --
Visibility Runway Visual Value (Statute Miles) --
Visibility (Statute Miles) 6
Air Temperature at event time (in degrees celsius) 20
Dew Point at event time (in degress fahrenheit) --
Wind Direction (degrees magnetic) 140
Variable Wind Indicator --
Wind Speed (knots) 12
Wind Velocity Indicator --
Wind Gust Indicator Not Gusting
Wind Gust (knots) --
Altimeter Setting at event time (in. Hg) --
Density Altitude (feet) --
Intensity of Precipitation --
METAR weather report --
Event Highest Injury Minor
On Ground, Fatal Injuries --
On Ground, Minor Injuries --
On Ground, Serious Injuries --
Injury Total Fatal --
Injury Total Minor 5
Injury Total None --
Injury Total Serious --
Injury Total All 5
Investigating Agency NTSB
NTSB Docket Number (internal use) 24804
NTSB Notification Source FAA-ROC
NTSB Notification Date Feb 7 2008 12:00AM
NTSB Notification Time --
Fiche Number and/or location -used to find docket information --
Date of most recent change to record Jan 26 2009 8:17AM
User who most recently changed record grol
Basic weather conditions Visual Meteorological Cond
FAA District Office Honolulu FSDO

Aircraft Involved

Aircraft #1

Aircraft Registration Number N698DM
NTSB Number SEA08FA071
Missing Aircraft Indicator --
Federal Aviation Reg. Part Part 135: Air Taxi & Commuter
Type of Flight Plan filed Company VFR
Flight plan Was Activated? Yes
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name MCDONNELL DOUGLAS
Aircraft Model 369E
Aircraft Series Identifier --
Aircraft Serial Number 348E
Certified Max Gross Weight 3000
Aircraft Category Helicopter
Aircraft Registration Class --
Aircraft is a homebuilt? No
Flight Crew Seats 1
Cabin Crew Seats --
Passenger Seats 4
Total number of seats on the aircraft 5
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection 100 Hour
Date of Last Inspection Jan 18 2008 12:00AM
Airframe hours since last inspection 66
Airframe Hours 9118
ELT Installed Yes
ELT Activated No
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name K&S Helicopters
Aircraft Owner Street Address --
Aircraft Owner City Kailua Kona
Aircraft Owner State HI
Aircraft Owner Country USA
Aircraft Owner Zipcode 96745
Operator is an individual? No
Operator Name Tropical Helicopters
Operator Same as Owner? No
Operator Is Doing Business As --
Operator Address Same as Owner? No
Operator Street Address --
Operator City Kailua Kona
Operator State HI
Operator Country USA
Operator Zip code 96745
Operator Code K2DA
Owner has at least one certificate Yes - certificate holder
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation --
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Non-scheduled
Indicates Domestic or International Flight Domestic
Operator carrying Pax/Cargo/Mail Passenger Only
Type of Flying (Per_Bus / Primary) --
Second Pilot on Board No
Departure Point Same as Event No
Departure Airport Code PHTO
Departure City HILO
Departure State HI
Departure Country USA
Departure Time 1425
Departure Time Zone HST
Destination Same as Local Flt dest & departure same, accident can occur anywhere
Destination Airport Code PHTO
Destination City HILO
Destination State HI
Destination Country USA
Specific Phase of Flight Descent - emergency
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Dec 17 2008 5:34PM
User who most recently changed record stam
Since inspection or accident Last Inspection
Event Location Runway Number and Location N/A
Runway Length --
Runway Width --
Sight Seeing flight Yes
Air Medical Flight No
Medical Flight --